Slider ValueChanged method command ( MVVM WPF Devexpress )

Question

I'm trying to bind a method to the value changed of a slider. I'm using devexpress poco,

XAML:

<ListView.ItemTemplate>
     <DataTemplate>
          <StackPanel Height="140" Margin="20">
               <Slider Height="100" Width="40" Margin="5" HorizontalAlignment="Left" TickFrequency="10" TickPlacement="BottomRight" Orientation="Vertical" Minimum="0" Maximum="100" Value="{Binding VolumeLevel}">
                    <dxmvvm:Interaction.Behaviors>
                         <dxmvvm:EventToCommand EventName="ValueChanged" Command="{Binding Path=VolumeChangedCommand}" />
                    </dxmvvm:Interaction.Behaviors>
               </Slider>
               <TextBlock Text="{Binding Name}" />
          </StackPanel>
     </DataTemplate>
</ListView.ItemTemplate>

My C# Code:

public void VolumeChanged()
{
     ...
}

The method never gets called.
Any suggestions?

Where is your method defined ? In which DataContext ? Assuming your current XAML code, it has to be defined in the model/item class. (Which would be in ListView.ItemsSource[i].VolumeChangedCommand) - Also your Command has to implement the ICommand interface. — Blacktempel
– Blacktempel, Commented Aug 28, 2018 at 4:30
ValueChanged is the name of the event. Your VolumeChangedCommand should get invoked whenever this event is raised. — mm8
– mm8, Commented Aug 28, 2018 at 15:27

Red Wei · Accepted Answer · 2018-08-28 05:19:43Z

Because you are binding the slider to a Command (this line: <dxmvvm:EventToCommand EventName="ValueChanged" Command="{Binding Path=VolumeChangedCommand}" />), and you don't have a Command so it won't fire. All you need to do is add a public Command VolumeChangedCommand

private ICommand _VolumeChangedCommand;
public ICommand VolumeChangedCommand
{
    get
    {
        if (_VolumeChangedCommand == null)
            _VolumeChangedCommand = new CommandImplement();
        return _VolumeChangedCommand ;
    }
    set
    {
        _VolumeChangedCommand = value;
    }
}

class CommandImplement: ICommand
{
    public bool CanExecute(object parameter)
    {
        return true;
    } 
    public event EventHandler CanExecuteChanged
    {
        add { CommandManager.RequerySuggested += value; }
        remove { CommandManager.RequerySuggested -= value; }
    } 

    public void Execute(object parameter)
    {
         VolumeChanged(); //Call your method or put your code here.
    }
}

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